The present relates to an agricultural harvesting machine with an intake device for conveying harvested crop material to downstream processing assemblies. The intake device is equipped with a foreign-object detection device for detecting foreign objects in the crop material flow, and with devices for braking the conveyance devices immediately when a foreign object is detected in the crop material.
Conveyance devices in the form of front harvesting attachments with foreign-object detection devices are typically used in agricultural harvesting machines, in forage harvesters in particular, in order to detect metal objects that may have entered the machine along with the crop material, e.g., an auger tine, a fence stake, an aluminum can, or a nail, and to then automatically shut off the conveyance device and downstream processing assemblies. The purpose is to prevent the metal objects from causing damage inside the agricultural harvesting machine and to ensure that they are removed before the crop material is fed to animals, who could ingest them and suffer injury or even death. In a typical design, a conveyance device of this type is composed of one or more pairs of intake rollers installed in series. Crop material that is picked up by a front harvesting attachment of the harvesting machine is drawn in by the rollers and directed, e.g., to a downstream chopper drum or another working unit.
A foreign-object detection device of this type is made known in DD 247 117 A3, with which a metal detector is located in a conveying roller that interacts with another conveying roller. The metal detector is typically fixed in position inside one of the front intake rollers. The detection region of the metal detector is formed by a magnetic measurement field generated by the magnet system. The magnetic measurement field is preferably oriented into the crop material flow, nearly perpendicularly from below, and/or often diagonally toward the front, in the direction of the front harvesting attachment. The detector signal that is measured is measured continually and compared with a predefined threshold value. If the threshold value is exceeded, a shut-off signal is sent to the conveyance device.
Foreign-object detection devices designed as stone detectors are also known, which are designed to protect the working units from damage caused by stones embedded in the crop material. A foreign-object detection device of this type is made known in DD-PS 247 118, with which acceleration is measured and evaluated at a part of the conveyance device that is movable perpendicularly to the conveyance device. When a certain acceleration threshold is exceeded, a stop signal is triggered and transmitted to the devices that brake the conveyance elements.
The disadvantage of the known foreign-object detection devices and their use in agricultural harvesting machines is that the agricultural harvesting machine is no longer able to pick up crop material, because all of the working units have stopped. Crop material can become jammed since, due to the operator's reaction time, a certain length of time passes from the instant when the foreign-object detection device is triggered until the harvesting machine is stopped. In particular, a forage harvester that is harvesting grass travels at high harvesting speeds. As a result, when a foreign object is detected, large swaths of grass are pushed in front of the forage harvester before it comes to a standstill. When it becomes necessary for the harvesting machine to pick up these piles of crop material after the foreign object has been removed, the harvesting machine often becomes overloaded, which may result in damage being done to the harvesting machine. If the crop material is a crop that is yet to be harvested, e.g., corn, it is driven over and pressed into the ground. Significant crop-material losses may therefore result if the foreign-object detection device is activated frequently.